Heterotopic ossification following uncemented total hip arthroplasty. Effect of the operative approach.

A consecutive series of 112 primary uncemented total hip arthroplasties using the same type of prosthesis was reviewed for the incidence and severity of heterotopic ossification (HO). Sixty-three of these patients underwent a posterior approach (group 1) and 49 underwent an anterolateral approach (group 2). The two groups were virtually identical when risk factors, such as age, sex, estimated blood loss, length of surgery, and diagnosis were compared. Patients in group 1 had a significantly lower incidence and severity of HO than those in group 2. The overall incidence of class III or IV HO was very low (8%), indicating that uncemented total hip arthroplasty in itself is not predisposed to moderate or severe degrees of HO. Patients undergoing uncemented total hip arthroplasty through an anterolateral approach had a higher incidence of HO than those undergoing a posterior approach in this series.